Both countries now allow officials to seize the passports of those suspected of planning travel to join a militant group. France has confiscated the passports of six individuals, but the UK was too late to stop three schoolgirls.

This is a still taken from CCTV issued by the Metropolitan Police in London on Monday Feb. 22, 2015, of 15-year-old Amira Abase, left, Kadiza Sultana,16, center, and Shamima Begum,15, going through Gatwick airport, before they caught their flight to Turkey on Tuesday Feb 17, 2015. The three teenage girls left the country in a suspected bid to travel to Syria to join the Islamic State extremist group.

Authorities in France have confiscated the passports of six French nationals allegedly planning to travel to Syria to join the self-described Islamic State, a first in the country’s invigorated campaign against Islamic extremism.

The incident puts into action a new law that allows authorities to seize passports and identity cards from French citizens suspected of planning to join a terrorist group overseas.

Countries across Europe have adopted similar policies to stem to flow of jihadist recruits to the Middle East. But they’re far from a panacea, a fact underscored last week when three British schoolgirls were believed to have flown to Istanbul en route to Syria to join the Islamic State.

British Prime Minister David Cameron acknowledged the shortcomings of his country's new antiterrorism policies in a speech he gave Saturday in London. According to The New York Times, the prime minister called on community and religious groups to do more to stop the radicalization of young Muslims. But he also promised that British authorities would do everything they could to find the missing teenagers.

“It does make a broader point, which is the fight against Islamist extremist terror is not just one that we can wage by the police and border control,” Mr. Cameron said, referring to the disappearance of the three girls. “We all have a role to play in stopping people from having their minds poisoned by this appalling death cult.”

On Monday, the families of the girls – Shamima Begum, Amira Abase, and Kadiza Sultana – issued emotional public appeals urging them to come home. The BBC reports that each family and the principal at the girls’ East London school said there were no signs that they were interested in extremism or of any plans to go abroad.

Weeks before the girls left Britain, police say they had become aware of their links to another British national suspected of traveling to Syria. The Associated Press reports that police are still searching for them in Turkey.

Meanwhile, French Interior Minister Bernard Cazeneuve announced Monday that authorities had seized the passports of six alleged French jihadists. An aide to Mr. Cazeneuve told Reuters that relatives reported on some of the men using a newly established telephone hotline, while others were identified by police investigations.

Cazeneuve told reporters that an additional 40 administrative bans on leaving the country are in preparation.

The Times reports that estimates from Europe’s counterterrorism coordinator suggest that more than 3,000 Europeans may have traveled to Syria and Iraq since early 2014, and could now represent roughly one-quarter of the foreign fighters in the region.

France’s government estimates that about 1,400 French citizens have links to radical Islamic recruitment cells and that about 400 are already fighting alongside militants in the Middle East. UK officials say at least 500 Britons have fought in the region, with some 300 having returned home.

Britain’s new law authorizes police to seize passports of suspects for up to 30 days. The law also allows police to stop citizens suspected of involvement with the Islamic State from entering the country.

The new law in France allows authorities to confiscate passports and identity cards of suspected jihadist recruits for up to six months, after which the order can be renewed. Suspects have the right to appeal the travel ban in court.